54 MORPHOLOGY AND EVOLUTION
one another in pronation and supination. And, as in most lower Primates, the carpus articulates with both radius and ulna. In the Simiidae it only articulates with
The femur is long and slender, with a globular head and a large great trochanter. No third trochanter exists. The linea aspera is poor. The tibia and fibula are separate.
Muscular System,—As the muscular system in the Simian Catarrhini is fully described in Chapter VI, only a few special points are mentioned here.
The cutaneous musculature consists of the derrno-humeralis, platysma myoides and sphincter colli. It is tlms equal to the musculature of the Lemurs, but it is more extensive than in the Simiidae.
The sterno-mastoid has sternal and clavicular components in some forms, but the clavicular fascicle is absent in some species. The sterno-hyoid and sterno-thyroid muscles are not peculiar, and the orno-hyoid has no central tendon.
The digastric muscle belongs to Parson's first type. The anterior bellies are fused to form a fan-shaped muscle with a posterior tendinous arcade into which the tendons of the posterior bellies are inserted. It exhibits a variable amount of fusion with the subjacent mylo-hyoid muscle, from which it evolved by splitting (Gegenbaur).
The pectoralis major has no clavicular origin, but springs from the fascia over the rectus abdominis and from the sternum. The pectoralis minor is inserted into the fascia over the coracoid process or into the capsule of the shoulder-joint. The subclavius is very strong.